The present invention relates to outboard motor drive shaft housing attachments and to methods of attaching an outboard motor drive shaft housing attachment, for increasing the performance of the outboard motor.
Outboard motors and inboard-outboard motors commonly have an internal combustion engine having an attachment bracket having a transom clamp and clamp screw formed thereon. The transom clamp supports the engine to the boat transom with a drive shaft extending from the engine along the transom of the boat into the water. The drive shaft typically has a drive shaft housing covering most of the drive shaft and a propeller is attached to the end of the drive shaft. Outboard engines typically have an anti-cavitation plate formed thereon and may have an exhaust port for exhausting gasses from the engine. Cooling liquid can be drawn from the water up the drive shaft housing to the engine and back into the water with the exhaust. Various types of attachments have been suggested in the past for accomplishing different purposes in the operation of the engine on a boat.
In U.S. Pat. No. 2,860,594 to Kiekhaefer, a splash deflector is attached to the housing to act as a splash guard to prevent the splashing of water into the back of the boat. In U.S. Pat. No. 3,980,035 to Johansson, an attitude control device for stern drive power boats, is utilized on a stern drive boat protruding down into the water. In contrast, the present invention attaches a fin plate above the water level. In U.S. Pat. No. 4,031,846 to Tone, an anticavitation shroud and rudder is attached to an inboard direct shaft boat under the water, while in U.S. Pat. No. 4,205,618 to Olsson, a trimming and stabilizing system for an outboard motor shaft housing is used to hold the boat in a planing position by extending into the water and controls the lifting of the stern. In U.S. Pat. No. 2,896,565 to Stevens, a hydraulic flow control plate is attached to the back of inboard boats to control the lifting of the stern. In U.S. Pat. No. 3,799,103 to Granholm, a stern drive unit trim tab is attached to an outboard motor drive shaft housing in a partially submerged position during normal operation. The U.S. Pat. No. 3,768,432 to Spaulding, provides a shallow water adapter for outboard motors, and provides a mounting to partially surround a propeller of an outboard motor which is attached to the outboard motor shaft housing. This unit is under water at all times to allow the propeller to pass through shallow water.
In contrast to these prior devices, the present invention has fin plates mounted above the water level for forcing air and water exiting from the bottom of the boat back towards the propeller to compress the air and water for removing the air and forcing the water into the propeller to thereby provide increased performance with the propeller, especially during rapid acceleration and high speed maneuvers.